Islamabad: Eleven students were killed and 22 others were injured in the twin blasts that rocked southwestern Pakistani city of Quetta on Saturday.

The first blast took place within the campus of Sardar Bahadur Khan Women's University at Brewery Road when the students were returning in back home in the university bus. The second blast took place at the Bolan Medical Complex where the injured girls were rushed for treatment after the first terror incident. The blast took place in the casualty ward.

According to the sources, the first bomb was planted in the stationary bus.

Police officials said 11 girls, all students of the university, were killed. Twenty-two injured people, most of them students, were rushed to the nearby Bolan Medical Complex. Doctors described the condition of three of them as serious. Several girls sustained severe burn injuries as the explosion triggered a fire in the bus.

Footage on television showed flames and black smoke emerging from the bus, which was reduced to a blackened heap of metal. Its roof was blown off and hung over the front. Security forces cordoned off the area and launched a search operation. The blast caused panic in the area and the university was evacuated.

No group has so far claimed responsibility for the attack.

The blast occurred hours after militants attacked and destroyed a historic 121-year-old building in Ziarat, about 120 km from Quetta, that was used by Pakistan's founder Muhammad Ali Jinnah in the last days of his life.

A policeman was killed in that attack, which was claimed by the Balochistan Liberation Army.